Heterotrophes

D-Glucose to L-Ascorbic Acid Fermentation. The direct heterotrophic fermentation of D-glucose to L-ascorbic acid with algae is... 

Organisms that require compounds manufactured by other organisms are called hetei oti ophs (other-nourishing). Many heterotrophs secrete enzymes (exoenzymes) that hydrolyze large molecules such as starch and cellulose to smaller units that can readily enter the cell. 

As a group, the MlC-causing bacteria may use almost any available organic carbon molecules, from simple alcohols or sugars to phenols to wood or various other complex pcJymers as food (heterotrophs), or they may fix CO9 (autotropha) as do plants. Some use inorganic elements or ions (e.g., NH or NO, CH, H, S, Fe, Mu, etc.), as sources of... 

Heterotrophic plate count n/a TT3 HPC has no health effects, but can indicate how effective treatment is at controlling microorganisms. HPC measures a range of bacteria that are naturally present in the environment... 

Headworks The facilities where wastewater enters a wastewater treatment plant. The headworks may consist of bar screens, comminutors, a wet well and pumps. Heterotroph A microorganism which uses organic matter for energy and growth. HRT Hours of Retention Time. 

FIGURE 18.8 The ATP cycle in cells. ATP is formed via photosynthesis in phototrophic cells or catabolism in heterotrophic cells. Energy-requiring cellular activities are powered by ATP hydrolysis, liberating ADP and Pj. 

Slime-Forming Bacteria. Several forms of bacteria produce a slimy capsule under certain environmental conditions. These organisms are heterotrophic, that is, they obtain their energy from organic sources such as sodium lactate. The reaction is... 

Fungi Heterotroph Carbohydrate (sugars, starch, pectin, cellulosics) As carbon source nh3, nh4+... 

Bacteria Heterotroph (methylotroph) Hydrocarbon derivatives (methanol) As carbon source NHs, NH4+... 

In Japan Chlorella spp has been produced for food in continuous aseptic systems in conventional bioreactors. The organisms are grown in the dark as heterotrophs using sucrose (in the form of molasses) or glucose as carbon and energy source. Production has been 2,000-3,000 tonnes per year at a selling price of (US)10-22 kg 1 (1990 prices). This product is sold as a high-value health food. 

Not appropriate. Medium C would allow the growth and isolation of heterotrophs (due to the inclusion of yeast extract) and is thus not elective for methylotrophs. Also for an industrial process an organism that does not require growth factors (such as vitamins) is preferable. Medium C might well enrich for methylotrophs requring such expensive growth factors. 

Carbon dioxide is produced as a result of metabolism of all heterotrophic organisms. The concentrations of CO2 in pore water of reduced sediments are therefore high. Autotrophic microorganisms consume CO2 in the oxidized part of the sediment, which can vary in depth from a meter in deep sea sediments to a few mm... 

This is not a reversible reaction in the strict sense and does not spontaneously seek equilibrium between products and reactants. The exothermic reverse reaction, respiration, occurs in a different part of phytoplankton cells or is mediated by heterotrophic organisms. 

Oceanic surface waters are efficiently stripped of nutrients by phytoplankton. If phytoplankton biomass was not reconverted into simple dissolved nutrients, the entire marine water column would be depleted in nutrients and growth would stop. But as we saw from the carbon balance presented earlier, more than 90% of the primary productivity is released back to the water column as a reverse RKR equation. This reverse reaction is called remineralization and is due to respiration. An important point is that while production via photosynthesis can only occur in surface waters, the remineralization by heterotrophic organisms can occur over the entire water column and in the underlying sediments. 

The subsequent fate of the assimilated carbon depends on which biomass constituent the atom enters. Leaves, twigs, and the like enter litterfall, and decompose and recycle the carbon to the atmosphere within a few years, whereas carbon in stemwood has a turnover time counted in decades. In a steady-state ecosystem the net primary production is balanced by the total heterotrophic respiration plus other outputs. Non-respiratory outputs to be considered are fires and transport of organic material to the oceans. Fires mobilize about 5 Pg C/yr (Baes et ai, 1976 Crutzen and Andreae, 1990), most of which is converted to CO2. Since bacterial het-erotrophs are unable to oxidize elemental carbon, the production rate of pyroligneous graphite, a product of incomplete combustion (like forest fires), is an interesting quantity to assess. The inability of the biota to degrade elemental carbon puts carbon into a reservoir that is effectively isolated from the atmosphere and oceans. Seiler and Crutzen (1980) estimate the production rate of graphite to be 1 Pg C/yr. 

Randerson, J. T., Thompson, M. V., Malmstrdm, C. M., Field, C. B. and Fung, I. Y. (1996). Substrate limitations for heterotrophs Implications for models that estimate the seasonal cycle of atmospheric CO2, Global Biogeochem. Cycles 10,585-602. 

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